This invention relates generally to a fire suppression system and, more particularly to a system for detecting and extinguishing fires in enclosures for collecting particulate material.
Historically, effective fire protection for installations in which bag filters are used for dust collection has proven quite challenging for a number of reasons. One problem results from the high air velocities which deter rapid detection of a fire in the collection enclosure. Although fixed temperature or rate-of-rise thermal detectors provide rapid and reliable fire detection in many types of process equipment, in dust collector enclosures, which normally operate with very high air velocities, a total inferno involving the entire collector may develop before there is sufficient thermal energy to alarm a heat detector. A fire at this late detection stage may have consumed or damaged most of the filter bags, support cages, venturis, tube sheet and possibly even the collector structure. Optical detectors, on the other hand, which respond to ultraviolet or infrared radiation emitted from the fire are "blinded" by dust and do not always operate effectively while requiring constant and regular inspection and maintenance. In addition, extinguishing a fire of significant magnitude with either water or a chemical extinguishing agent is difficult and messy. Large quantities of extinguishing agent are needed to thoroughly drench all the filter bags and costly downtime results until the collector enclosure is refurbished or replaced.